package repo

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"sync"

	"browser.local/platform/domain"
)

type StoreSnapshot struct {
	Users           []domain.User           `json:"users"`
	AIProviders     []domain.AIProvider     `json:"aiProviders"`
	GamePlugins     []domain.GamePlugin     `json:"gamePlugins"`
	ServerInstances []domain.ServerInstance `json:"serverInstances"`
	RunEndpoints    []domain.RunEndpoint    `json:"runEndpoints"`
	Jobs            []domain.Job            `json:"jobs"`
	Artifacts       []domain.Artifact       `json:"artifacts"`
	LogStreams      []domain.LogStream      `json:"logStreams"`
	AuditEvents     []domain.AuditEvent     `json:"auditEvents"`
}

type FileStore struct {
	*MemoryStore
	path      string
	persistMu sync.Mutex
}

func NewFileStore(path string) (*FileStore, error) {
	path = strings.TrimSpace(path)
	if path == "" {
		return nil, fmt.Errorf("metadata path is required")
	}
	store := &FileStore{
		MemoryStore: NewMemoryStore(),
		path:        path,
	}
	if err := store.load(); err != nil {
		return nil, err
	}
	return store, nil
}

func (store *FileStore) MetadataPath() string {
	return store.path
}

func (store *FileStore) Users() UserRepository {
	return &persistentRepository[domain.User, domain.UserFilter]{repository: store.MemoryStore.users, persist: store.persist}
}

func (store *FileStore) AIProviders() AIProviderRepository {
	return &persistentRepository[domain.AIProvider, domain.AIProviderFilter]{repository: store.MemoryStore.aiProviders, persist: store.persist}
}

func (store *FileStore) GamePlugins() GamePluginRepository {
	return &persistentRepository[domain.GamePlugin, domain.GamePluginFilter]{repository: store.MemoryStore.gamePlugins, persist: store.persist}
}

func (store *FileStore) ServerInstances() ServerInstanceRepository {
	return &persistentRepository[domain.ServerInstance, domain.ServerInstanceFilter]{repository: store.MemoryStore.serverInstances, persist: store.persist}
}

func (store *FileStore) RunEndpoints() RunEndpointRepository {
	return &persistentRepository[domain.RunEndpoint, domain.RunEndpointFilter]{repository: store.MemoryStore.runEndpoints, persist: store.persist}
}

func (store *FileStore) Jobs() JobRepository {
	return &persistentJobRepository{
		persistentRepository: &persistentRepository[domain.Job, domain.JobFilter]{repository: store.MemoryStore.jobs, persist: store.persist},
		repository:           store.MemoryStore.jobs,
	}
}

func (store *FileStore) Artifacts() ArtifactRepository {
	return &persistentRepository[domain.Artifact, domain.ArtifactFilter]{repository: store.MemoryStore.artifacts, persist: store.persist}
}

func (store *FileStore) LogStreams() LogStreamRepository {
	return &persistentRepository[domain.LogStream, domain.LogStreamFilter]{repository: store.MemoryStore.logStreams, persist: store.persist}
}

func (store *FileStore) AuditEvents() AuditEventRepository {
	return &persistentRepository[domain.AuditEvent, domain.AuditEventFilter]{repository: store.MemoryStore.auditEvents, persist: store.persist}
}

func (store *FileStore) load() error {
	data, err := os.ReadFile(store.path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return fmt.Errorf("read metadata snapshot: %w", err)
	}
	if len(strings.TrimSpace(string(data))) == 0 {
		return nil
	}
	var snapshot StoreSnapshot
	if err := json.Unmarshal(data, &snapshot); err != nil {
		return fmt.Errorf("decode metadata snapshot: %w", err)
	}
	store.loadSnapshot(snapshot)
	return nil
}

func (store *FileStore) persist() error {
	store.persistMu.Lock()
	defer store.persistMu.Unlock()

	snapshot := store.snapshot()
	data, err := json.MarshalIndent(snapshot, "", "  ")
	if err != nil {
		return fmt.Errorf("encode metadata snapshot: %w", err)
	}
	if err := os.MkdirAll(filepath.Dir(store.path), 0o755); err != nil {
		return fmt.Errorf("create metadata directory: %w", err)
	}
	tmpPath := store.path + ".tmp"
	if err := os.WriteFile(tmpPath, data, 0o600); err != nil {
		return fmt.Errorf("write metadata snapshot: %w", err)
	}
	if err := os.Rename(tmpPath, store.path); err != nil {
		return fmt.Errorf("replace metadata snapshot: %w", err)
	}
	return nil
}

func (store *FileStore) snapshot() StoreSnapshot {
	return StoreSnapshot{
		Users:           snapshotRepository(store.MemoryStore.users),
		AIProviders:     snapshotRepository(store.MemoryStore.aiProviders),
		GamePlugins:     snapshotRepository(store.MemoryStore.gamePlugins),
		ServerInstances: snapshotRepository(store.MemoryStore.serverInstances),
		RunEndpoints:    snapshotRepository(store.MemoryStore.runEndpoints),
		Jobs:            snapshotRepository(store.MemoryStore.jobs.memoryRepository),
		Artifacts:       snapshotRepository(store.MemoryStore.artifacts),
		LogStreams:      snapshotRepository(store.MemoryStore.logStreams),
		AuditEvents:     snapshotRepository(store.MemoryStore.auditEvents),
	}
}

func (store *FileStore) loadSnapshot(snapshot StoreSnapshot) {
	loadRepository(store.MemoryStore.users, snapshot.Users)
	loadRepository(store.MemoryStore.aiProviders, snapshot.AIProviders)
	loadRepository(store.MemoryStore.gamePlugins, snapshot.GamePlugins)
	loadRepository(store.MemoryStore.serverInstances, snapshot.ServerInstances)
	loadRepository(store.MemoryStore.runEndpoints, snapshot.RunEndpoints)
	loadRepository(store.MemoryStore.jobs.memoryRepository, snapshot.Jobs)
	loadRepository(store.MemoryStore.artifacts, snapshot.Artifacts)
	loadRepository(store.MemoryStore.logStreams, snapshot.LogStreams)
	loadRepository(store.MemoryStore.auditEvents, snapshot.AuditEvents)
}

type mutableRepository[T any, F any] interface {
	Create(T) error
	Get(string) (T, error)
	List(F) ([]T, error)
	Update(T) error
}

type persistentRepository[T any, F any] struct {
	repository mutableRepository[T, F]
	persist    func() error
}

func (repository *persistentRepository[T, F]) Create(value T) error {
	if err := repository.repository.Create(value); err != nil {
		return err
	}
	return repository.persist()
}

func (repository *persistentRepository[T, F]) Get(id string) (T, error) {
	return repository.repository.Get(id)
}

func (repository *persistentRepository[T, F]) List(filter F) ([]T, error) {
	return repository.repository.List(filter)
}

func (repository *persistentRepository[T, F]) Update(value T) error {
	if err := repository.repository.Update(value); err != nil {
		return err
	}
	return repository.persist()
}

type persistentJobRepository struct {
	*persistentRepository[domain.Job, domain.JobFilter]
	repository JobRepository
}

func (repository *persistentJobRepository) GetByIdempotency(runEndpointID string, idempotencyKey string) (domain.Job, error) {
	return repository.repository.GetByIdempotency(runEndpointID, idempotencyKey)
}

func snapshotRepository[T any, F any](repository *memoryRepository[T, F]) []T {
	repository.mu.RLock()
	defer repository.mu.RUnlock()

	ids := make([]string, 0, len(repository.byID))
	for id := range repository.byID {
		ids = append(ids, id)
	}
	sort.Strings(ids)
	values := make([]T, 0, len(ids))
	for _, id := range ids {
		values = append(values, repository.copyOf(repository.byID[id]))
	}
	return values
}

func loadRepository[T any, F any](repository *memoryRepository[T, F], values []T) {
	repository.mu.Lock()
	defer repository.mu.Unlock()

	repository.byID = map[string]T{}
	for _, value := range values {
		repository.byID[repository.idOf(value)] = repository.copyOf(value)
	}
}